Aqueous latex and dispersion of inorganic pigment particles comprising the same

Abstract

The present disclosure relates to an aqueous latex and a process for the preparation thereof. In particular, the present disclosure relates to an aqueous latex useful as a spacing extender for inorganic pigment particles. The present disclosure also relates to a dispersion of inorganic pigment particles comprising the aqueous latex and to an aqueous coating composition comprising the aqueous latex and inorganic pigment particles.

What is claimed is: 
     
       1. An aqueous dispersion of polymeric particles prepared through emulsion polymerization using monomers comprising:
 i) 0.1 to 20% by weight of at least one ethylenically unsaturated monomer containing an anchor functionality and a moiety containing poly(oxyethylene); 
 ii) 0 to 20% by weight of at least one ethylenically unsaturated monomer with a carboxylic acid functionality; and 
 iii) 60 to 99.9% by weight of at least one ethylenically unsaturated monomer other than monomers i) and ii), 
 wherein the weight % is relative to the total weight of the monomers i), ii) and iii); and 
 wherein the polymeric particles have a glass transition temperature of greater than 60° C. up to about 110° C. 
 
     
     
       2. The aqueous dispersion of polymeric particles as claimed in  claim 1 , wherein the polymeric particles have a number average particle size in the range of from 30 to 150 nm. 
     
     
       3. The aqueous dispersion of polymeric particles of  claim 1 , wherein the ethylenically unsaturated monomer i) has a structure represented by formula (I): 
       
         
           
           
               
               
           
         
         in which, 
         R represents H or methyl; Bg represents a divalent bridged group of —CO— or —CHR′— wherein R′ represents H or methyl; A represents —(CH 2 CH 2 O) r —, in which r represents a value in the range of 1 to 54 or —(CH 2 CH 2 O) p (C y H 2y O) q —, in which the structural units are connected with each other in arbitrary order, the subscripts p and q represent the statistic sum of the corresponding structural units in the range of 1 to 54 with the ratio of p to q being in the range of 1:1 to 10:1and y represents an integer in the range of 3 to 8; X represents an anchor functionality; and n is 1 or 2. 
       
     
     
       4. The aqueous dispersion of polymeric particles as claimed in  claim 3 , wherein the anchor functionality is selected from the group consisting of phosphoric acid functionality, phosphate salt functionality, ammonium salt functionality, amine functionality and hydroxyl functionality. 
     
     
       5. The aqueous dispersion of polymeric particles as claimed in  claim 4 , wherein the ethylenically unsaturated monomer i) has a structure represented by formula (I-1): 
       
         
           
           
               
               
           
         
         in which, 
         R, Bg, A and n are defined as above; M represents alkali metal ion; and x is at each occurrence 0 or 1. 
       
     
     
       6. The aqueous dispersion of polymeric particles of  claim 1 , wherein the ethylenically unsaturated monomer i) is present in an amount of 0.2 to 10% by weight relative to the total weight of monomers i), ii) and iii). 
     
     
       7. The aqueous dispersion of polymeric particles of  claim 1 , wherein the ethylenically unsaturated monomer ii) is selected from the group consisting of acrylic acid, methacrylic acid, beta-acryloxy propionic acid, ethacrylic acid, alpha-chloroacrylic acid, crotonic acid, alpha-phenylacrylic acid, cinnamic acid, chlorocinnamic acid, itaconic acid, maleic acid and the combination thereof. 
     
     
       8. The aqueous dispersion of polymeric particles as claimed in  claim 7 , wherein the ethylenically unsaturated monomer ii) comprises acrylic acid, methacrylic acid or the combination thereof. 
     
     
       9. The aqueous dispersion of polymeric particles of  claim 7 , wherein the ethylenically unsaturated monomer ii) is present in an amount of 0.2 to 10% by weight relative to the total weight of monomers i), ii) and iii). 
     
     
       10. The aqueous dispersion of polymeric particles of  claim 1 , wherein the ethylenically unsaturated monomer iii) is selected from the group consisting of styrene, alpha-methylstyrene, vinyltoluene, vinylnaphthalene, vinyl acetate, vinyl versarate, acrylonitrile, methacrylonitrile, C 1-20  alkyl esters of (meth)acrylic acid, alkoxyalkyl (meth)acrylate and the combination thereof. 
     
     
       11. The aqueous dispersion of polymeric particles as claimed in  claim 10 , wherein the ethylenically unsaturated monomer iii) comprises relative to the total weight of monomers i), ii) and iii), 50 to 99.9% by weight of styrene, 0 to 40% by weight of butyl acrylate and 0 to 49.9% by weight of methyl methacrylate. 
     
     
       12. A process for the preparation of an aqueous dispersion of polymeric particles comprising carrying out an emulsion polymerization of monomers in the presence of an emulsifier and a radical initiator, the monomers comprising:
 i) 0.1 to 20% by weight of at least one ethylenically unsaturated monomer containing an anchor functionality and a moiety containing poly(oxyethylene); 
 ii) 0 to 20% by weight of at least one ethylenically unsaturated monomer with a carboxylic acid functionality; and 
 iii) 60 to 99.9% by weight of at least one ethylenically unsaturated monomer other than monomers i) and ii), 
 wherein the weight% is relative to the total weight of the monomers i), ii) and iii); and 
 wherein the polymeric particles have a glass transition temperature greater than 60° C. up to about 110° C. 
 
     
     
       13. The process as claimed in  claim 12 , wherein the polymeric particles have a number average particle size in the range of from 30 to 150 nm. 
     
     
       14. The process of  claim 12 , wherein the ethylenically unsaturated monomer i) has a structure represented by formula (I): 
       
         
           
           
               
               
           
         
         in which, 
         R represents H or methyl; Bg represents a divalent bridged group of —CO— or —CHR′— wherein R′ represents H or methyl; A represents —(CH 2 CH 2 O) r —, in which r represents a value in the range of 1 to 54 or —(CH 2 CH 2 O) p (C y H 2y O) q —, in which the structural units are connected with each other in arbitrary order, the subscripts p and q represent the statistic sum of the corresponding structural units in the range of 1 to 54 with the ratio of p to q being in the range of 1:1 to 10:1 and y represents an integer in the range of 3 to 8; X represents an anchor functionality, and n is 1 or 2. 
       
     
     
       15. The process as claimed in  claim 14 , wherein the anchor functionality is selected from the group consisting of phosphoric acid functionality, phosphate salt functionality, ammonium salt functionality, amine functionality and hydroxyl functionality. 
     
     
       16. The process as claimed in  claim 15 , wherein the ethylenically unsaturated monomer i) has a structure represented by formula (I-1): 
       
         
           
           
               
               
           
         
         in which, 
         R, Bg, A and n are defined as above; M represents alkali metal ion; and x is at each occurrence 0 or 1. 
       
     
     
       17. The process of  claim 12 , wherein the ethylenically unsaturated monomer i) is present in an amount of 0.2 to 10% by weight relative to the total weight of monomers i), ii) and iii). 
     
     
       18. A dispersion of inorganic pigment particles comprising inorganic pigment particles, an aqueous dispersion of polymeric particles of  claim 1 , and a dispersion medium. 
     
     
       19. The dispersion of inorganic pigment particles as claimed in  claim 18 , wherein the inorganic pigment particles comprise titanium dioxide particles in the form of slurry or powder. 
     
     
       20. The dispersion of inorganic pigment particles as claimed in  claim 18 , wherein the dispersion medium is water, an organic solvent miscible with water or the combination thereof. 
     
     
       21. The process as claimed in  claim 12 , wherein the polymeric particles have a glass transition temperature of at least 70° C. up to about 110° C. 
     
     
       22. The process as claimed in  claim 12 , wherein the polymeric particles have a glass transition temperature of at least 80° C. up to about 105° C.